Failure analysis of a special vehicle engine connecting rod

• Published in: Engineering failure analysis 2017-09, Vol.79, p.98-109
• Main Authors: Rakic, Slavko, Bugaric, Ugljesa, Radisavljevic, Igor, Bulatovic, Zeljko
• Format: Article
• Language: English
• ISSN: 1350-6307; 1873-1961
• DOI: 10.1016/j.engfailanal.2017.04.014

This paper presents failure analysis of the connecting rod used in a 12-cylinder diesel engine set on a special vehicle. The fracture of the connecting rod occurred during the engine test in laboratory conditions. Chemical and metallographic analysis as well as mechanical testing have confirmed that the material properties of the connecting rod met the requirements of standard specification and technical documentation. Linear finite element (FE) analysis was performed to evaluate stress state of the connecting rod under maximum load. The results of FE analysis showed that the position of the fracture is consistent with the zone of highest stress. Fractographic analysis has not been able to reveal the main cause of mechanism of fracture due to substantially damaged fracture surface. Inadequate machining, absence of polishing and highest stress in the region of fracture were identified as the main causes of failure. Finally, the engine had been working at maximum load for a longer period of time that also led to the breakage of the connecting rod. •The connecting rod of the special vehicle engine fractured during the test.•The finite element analysis showed the highest stress in the fracture origin area.•The connecting rod material met the requirements of the standard specification.•The bad machining of the connecting rod was observed.•The absence of the polishing of the connecting rod was observed.